DTC P0011, P0012, P0021, P0022 VVT VCT Understanding, Testing and Repairing

Mercedes Benz Workshop Information System
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BMW Technical Information System
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These codes refer to the VVT (variable valve timing) or VCT (variable camshaft timing) system on the vehicle and refer to an engine of either a single or dual bank design. The lower number codes refer to Bank 1 and the higher number codes refer to Bank 2.

For an explanation of the system electrical operation and overview of the manufacturer reasoning to install this system in the vehicles see the P0010 article.

The symptoms of course are the Check Engine Light illuminated (Malfunction Indicator Lamp), possibly rough running , hard starting, poor idling or even stalling for all of the DTCs. The symptoms are of very little use in the diagnosis except for confirmation.

The system consists of the engine lubrication system (the oil pump, filter and engine oil), a specially designed camshaft, an Oil Control Valve (OCV), also called a solenoid valve, and the car's PCM (powertrain control module).

The system is rather simplistic in design; it is a solenoid (Oil Control Valve), which the PCM applies the ground circuit at the correct time and in the correct amount, which controls engine oil flow to the camshaft timing plate. However for the system to function properly requires that oil and filter changes have been performed properly and at the correct frequency. It also requires that the timing belt be properly installed.

DTC P0011 and P0021 indicate the timing is too advanced. DTC P0012 and P0022 indicate the timing is too retarded. When you consider what these codes are saying, it becomes obvious that these codes are more indicative of a mechanical failure or the results of poor maintenance. These four DTCs could be an electrically failed OCV but they would most likely be accompanied by a P0010 or P0020 code.

For the P0011 and P0021 codes to appear indicates that the OCV solenoid is mechanically open at all times and allowing engine oil to move the intake camshaft(s) without PCM intervention.

For the P0012 and P0022 codes to appear indicates that the OCV solenoid is mechanically closed at all times and not allowing engine oil to move the intake camshaft(s) when commanded (ground applied) by the PCM.

If the oil changes have not been performed properly and at the correct frequency it can result in lots of gum and varnish deposits which could render the OCV inoperative or incapable of working.

For the Professional;

Start your diagnostics with a proper OBD2 Baseline Diagnostic Procedure, to ascertain what condition the vehicle is in. This is followed by a look into the maintenance records. Items of importance would be;

Has the timing belt been replaced recently?

Has the oil changes been performed properly with the correct viscosity and grade of oil and at the proper frequency?

Has the engine been replaced?

If this is a used vehicle and no records have been provided, inspect to see if the timing belt has recently been serviced and whether the crankshaft camshaft timing alignment is off.

It may be advisable to flush the oil system with a flush designed for this. Unfortunately, if the MIL is already on, it is doubtful that simply flushing the oil will solve the problem. Flushing the oil should be a one-time preventative maintenance item, if there are no records of maintenance.

Keep in mind that if everything tests good on a thoroughly warmed engine, and fails on a cold engine this clearly tells you that a gum and varnish problem exists and simply changing the OCV will not totally solve the problem. It will recheck!

If you replace the OCV for any of these codes, you should check with your management about the possibility of flushing the oil system, and placing this vehicle on a more properly scheduled maintenance program.

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       Fix It Right The First Time!

Fortunately, everything you need everything you need to fix it right the first time is right here!

To access the sensor and data from your Engine Controller (PCM) you will need:

Professional Quality Scan Tool such as our 2X80S Scan Tool series.

Professional Quality Automotive Diagnostic Software such as OBD2 Spy, OBD 2007, or Scan Master.

If you understand how the systems were designed to work and how to test them, great! Otherwise you will need factory product service training manuals that will teach you and guide you through the diagnostic phase.

You might also need the manufacturer factory service manuals and data systems that provide specifications and details relative to your specific model.

Or aftermarket data systems such as All Data, Mitchell On Demand, Auto Data, Bosch, and others.

Everything is available here for you as a single source for all your needs. The aftermarket data systems are available in our members only area by direct shipment from the distributor at great pricing.

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